If terralt is multi colored gravel looking stuff, then I'm all for it. Is it better than Flourite, I have no idea. When I put together a tank, I use dupla laterite and terralit. I have not had much experience with Flourite due to its price. I realize terralit is also expensive, but I have had good results with it and at one point found it for a very good price several years ago. Even on my parent's low tech tank, I used laterite and the corresponding bag of terralit for a 36 gallon aquarium. She gets wonderful growth.
take a look here if you like:
http://homepage.mac.com/ddaquaria/ddaquaria/Corner36/